On Sun, May 02, 2021 at 12:17:51PM +0200, Christophe JAILLET wrote:
> Le 02/05/2021 à 00:50, Khaled ROMDHANI a écrit :
> > Fix the warning: variable 'zone' is used
> > uninitialized whenever '?:' condition is true.
> >
> > Fix that by preventing the code to reach
> > the last assertion. If the variable 'mirror'
> > is invalid, the assertion fails and we return
> > immediately.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Khaled ROMDHANI <khaledromdhani216@xxxxxxxxx>
> > ---
> > fs/btrfs/zoned.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> > index 8250ab3f0868..23da9d8dc184 100644
> > --- a/fs/btrfs/zoned.c
> > +++ b/fs/btrfs/zoned.c
> > @@ -145,7 +145,7 @@ static inline u32 sb_zone_number(int shift, int mirror)
> > case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break;
> > default:
> > ASSERT((u32)mirror < 3);
> > - break;
> > + return 0;
> > }
> > ASSERT(zone <= U32_MAX);
> >
> > base-commit: b5c294aac8a6164ddf38bfbdd1776091b4a1eeba
> >
> Hi,
>
> just a few comments.
>
> If I understand correctly, what you try to do is to silence a compiler
> warning if no case branch is taken.
>
> First, all your proposals are based on the previous one.
> I find it hard to follow because we don't easily see what are the
> differences since the beginning.
>
> The "base-commit" at the bottom of your mail, is related to your own local
> tree, I guess. It can't be used by any-one.
>
> My understanding it that a patch, should it be v2, v3..., must apply to the
> current tree. (In my case, it is the latest linux-next)
> This is not the case here and you have to apply each step to see the final
> result.
>
> Should this version be fine, a maintainer wouldn't be able to apply it
> as-is.
>
> You also try to take into account previous comments to check for incorrect
> negative values for minor and catch (the can't happen today) cases, should
> BTRFS_SUPER_MIRROR_MAX change and this function remain the same.
>
> So, why hard-coding '3'?
> The reason of magic numbers are hard to remember. You should avoid them or
> add a comment about it.
>
> My own personal variation would be something like the code below (untested).
>
> Hope this helps.
>
> CJ
>
>
> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> index 70b23a0d03b1..75fe5f001d8b 100644
> --- a/fs/btrfs/zoned.c
> +++ b/fs/btrfs/zoned.c
> @@ -138,11 +138,14 @@ static inline u32 sb_zone_number(int shift, int
> mirror)
> {
> u64 zone;
>
> - ASSERT(mirror < BTRFS_SUPER_MIRROR_MAX);
> + ASSERT(mirror >= 0 && mirror < BTRFS_SUPER_MIRROR_MAX);
> switch (mirror) {
> case 0: zone = 0; break;
> case 1: zone = 1ULL << (BTRFS_SB_LOG_FIRST_SHIFT - shift); break;
> case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break;
> + default:
> + ASSERT(! "mirror < BTRFS_SUPER_MIRROR_MAX but not handled above.");
> + return 0;
> }
>
> ASSERT(zone <= U32_MAX);
>
Thank you for all of your comments. Yes, of course, they will help me.
I will try to handle that more properly.
Thanks again.
